Method of planning, trajectory computation, predictions and guidance for compliance with an aircraft flypast time constraint

1. A method of planning, trajectory computation, predictions and guidance for compliance with an aircraft flypast time constraint (RTA), using a flight management system (FMS), a library, and a database of performance of the aircraft and data defining current conditions of flight, comprising the following steps: gathering of the current flight conditions, provisioning, on a basis of the library, computations of speeds characteristic of climbing, cruising and descent, as a function of minimum, maximum, and optimal speeds with a view to deriving maximum benefit from a flight envelope of an aeroplane and for a requirement of achieving the lowest possible fuel consumption; managing predictions of lateral trajectory and of profile of altitude and of speeds (4D trajectory) and consideration of predictions of a weight of the aircraft throughout an entire trajectory; defining, throughout a mission profile, margins to be preserved for RTA speeds with respect to limits of the flight envelope, the margins defined using at least one of a current flight plan, an active segment of the flight plan, a current phase, attitudes of the aircraft and a characterization of a current wind, and by defining a percentage between the margins and at least one of the following characteristics: maximum speed of the flight envelope, minimum speed of the flight envelope, and optimal speed of the flight envelope; provisioning, on a basis of a given 4D profile and of a time prediction associated with a RTA point, of factors for adapting speeds per flight phase so as to obtain a new 4D trajectory adapted to a RTA constraint; controlling with the FMS iterations for managing a convergence of computations of flight duration towards a duration corresponding to compliance with the time constraint and management of a 4D reference profile; and supervising with the FMS a current prediction of time of flypast at the RTA point, capable of signalling, alerting or controlling readjustments of the 4D profile as a function of a current compliance with an estimated time of arrival in relation to the RTA constraint.

2. The method according to claim 1 , further comprising a prior step of preprocessing initial data so as to choose between several strategies for computing the RTA speeds profile.

3. The method according to claim 1 , further comprising at least one step of readapting the trajectory and a vertical profile when during a mission, the data outside the aircraft have caused the time predictions to drift and when the RTA constraint is no longer complied with under initial speeds and trajectory assumptions.

4. The method according to claim 1 , wherein an apportionment of the profile of speeds as the result of the computation of the predictions of vertical profile on the basis of a lateral trajectory is performed as CAS or MACH values along “vertical” segments and not necessarily related to points of a lateral flight plan.

5. A device for planning, trajectory computation, predictions and guidance for compliance with an aircraft flypast time constraint (RTA), using a database of performance of an aircraft and data defining current conditions of a flight, associated with one of an FMS and mission preparation equipment, comprising: a trajectory and predictions manager; a library of computations of characteristic speeds making it possible to provide values of speeds characteristic of climbing, cruising and descent, as a function of minimum, maximum, and optimal speeds with a view to deriving maximum benefit from a flight envelope of an aeroplane and for a requirement of achieving the lowest possible fuel consumption, in conjunction with the database; a function defining, throughout a mission profile, margins to be preserved for RTA speeds with respect to limits of the flight envelope, the margins defined using at least one of a current flight plan, an active segment of the flight plan, a current phase, attitudes of the aircraft and a characterization of a current wind, and by defining a percentage between the margins and at least one of the following characteristics: maximum speed of the flight envelope, minimum speed of the flight envelope, and optimal speed of the flight envelope; a function which, on a basis of a given 4D profile and of a time prediction associated with a RTA point, gives factors for adapting speeds per flight phase so as to obtain a new 4D trajectory adapted to a RTA constraint, a controller that controls iterations supervising a convergence of computations of flight duration to RTA points, and arbitrating a publication and fixing of a 4D reference profile on which a mission will be based with an aim of compliance with the RTA constraint, and a monitor that monitors a current prediction of time of flypast at a RTA point, capable of signalling, alerting or controlling readjustments of the 4D profile as a function of a current compliance with an estimated time of arrival in relation to the RTA constraint.